1. Field of the Invention
The present invention relates to a chip antenna which is used for a mobile communication terminal, local area networks (LAN), or at blue tooth (BT) band, and more particularly to a chip antenna with parasitic elements which forms an electromagnetic coupling with conductive patterns, thereby generating double or multiple resonances between the parasitic elements and the conductive patterns connected to a power-feeding terminal. Therefore, the chip antenna of the present invention is miniaturized, has a broad bandwidth, and removes a peak peripherally generated around usable frequency band by resonance of the chip antenna.
2. Description of the Related Art
Generally, a known mobile communication terminal comprises a main body, and a bar-type antenna extruding from the upper surface of the main body. The bar-type antenna of the mobile communication terminal serves to transmit and receive radio waves. Resonant frequency of the bar-type antenna of the mobile communication terminal is determined by the total length of a conductor of the antenna. However, since the bar-type antenna for mobile communication terminal extrudes from the main body, this type of the antenna does not satisfy the recent trend of the mobile communication terminal toward miniaturization.
A conventional chip antenna for overcoming this disadvantage is illustrated in FIG. 1. FIG. 1 is a see-through perspective view of this conventional chip antenna.
With reference to FIG. 1, the conventional chip antenna comprises a substrate 1, a conductor 2, and a power-feeding terminal 3. The substrate 1 is made of a dielectric material. The conductor 2 is helically disposed within the substrate 1 or on the substrate 1. The conductor 2 has two parallelly-arranged conductive patterns. The power-feeding terminal 3 is formed on the surface of the substrate 1 in order to apply a voltage to the conductor 2. One conductive pattern of the conductor 2 is connected to the other conductive pattern of the conductor 2 at a turning section 2a. 
In the aforementioned conventional chip antenna, as the coiling number (L) of the conductor increases, the resonant frequency (fo) is lowered. Further, the coiling number (L) of the conductor is inversely proportional to the bandwidth of the antenna. Therefore, the conductor of the conventional chip antenna is constructed so that two conductive patterns of the conductor 2 are parallelly arranged at the turning section 2a, thereby not increasing the coiling number (L) of the conductor and enlarging an opposite area between the conductor and the ground, thereby increasing the capacitance (C) generated between the conductor and the ground and broadening the bandwidth.
However, the broadened bandwidth of the aforementioned conventional chip antenna is not sufficient. Further, since the antenna characteristics are determined by the interval between two parallelly-arranged conductive patterns of the conductor, the reliability of the conventional chip antenna is deteriorated.
FIG. 2 is a see-though perspective view of another conventional chip antenna. With reference to FIG. 2, another conventional chip antenna comprises a base block 10, inverted F-type first conductive patterns 11, and inverted L-type second conductive patterns 12. The base block 10 is made of a dielectric or magnetic material. The base block 10 includes an upper surface, a lower surface opposite to the upper surface, and four side surfaces disposed between the upper surface and the lower surface. The inverted F-type first conductive patterns 11 are formed on a part of the base block 10. The inverted L-type second conductive patterns 12 are also formed on another part of the base block 10. The inverted F-type first conductive patterns 11 are connected in parallel with the inverted L-type second conductive patterns 12.
The conventional chip antenna of FIG. 2 has an advantage in that the chip antenna can be miniaturized without changing the antenna characteristics. Further, the resonant frequencies of respective conductive patterns are closed to each other, thereby broadening the bandwidth at a single frequency.
However, the antenna characteristics are deteriorated by structural and/or material factors due to the miniaturization of the aforementioned conventional chip antenna. Further, with only two independent conductive patterns, since it is difficult to generate double or multiple resonances, this conventional chip antenna is limited in broadening the bandwidth and improving the gain of the chip antenna.
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a chip antenna using parasitic elements for forming an electromagnetic coupling with conductor patterns, thereby generating double or multiple resonances between the parasitic elements and the conductor patterns connected to a power-feeding terminal.
It is another object of the present invention to provide a chip antenna with parasitic elements, which is miniaturized, has a broad bandwidth, and removes a peak peripherally generated around usable frequency band by resonance of the chip antenna.
In accordance with one aspect of the present invention, the above and other objects can be accomplished by the provision of a chip antenna including: a base block made of one selected from a dielectric material and a magnetic material and including an upper surface, a lower surface opposite to the upper surface, and four side surfaces disposed between the upper surface and the lower surface; inverted F-type first conductive patterns formed on a part of the base block; inverted L-type second conductive patterns formed on another part of the base block and connected in parallel with the first conductive patterns; and parasitic elements spaced from the first and second conductive patterns by a designated distance and forming an electromagnetic coupling with the first and second conductive patterns.
In accordance with a further aspect of the present invention, there is provided a chip antenna including: a rectangular parallelepiped base block made of one selected from a dielectric material and a magnetic material; first conductive patterns including side electrodes wound in a spiral form on a part of the base block, upper and lower electrodes connected to the side electrodes, and bending portions formed on the upper and lower electrodes; second conductive patterns disposed within the base block between the upper electrodes and the lower electrodes and connected in parallel with the first conductive patterns; a power-feeding terminal and a ground terminal, both connected to the first conductive patterns; an impedance-controlling electrode connected to the upper end of the base block between the second conductive patterns and the power-feeding terminal to control the impedance; and parasitic elements spaced from the first and second conductive patterns by a designated distance and forming an electromagnetic coupling with the first and second conductive patterns.
In accordance with another aspect of the present invention, there is provided a chip antenna including: a rectangular parallelepiped base block made of one selected from a dielectric material and a magnetic material; first conductive patterns including side electrodes wound in a spiral form on a part of the base block, upper and lower electrodes connected to the side electrodes, and bending portions formed on the upper and lower electrodes; second conductive patterns disposed within the base block between the upper electrodes and the lower electrodes and connected in parallel with the first conductive patterns; a power-feeding terminal and a ground terminal, both connected to the first conductive patterns; an impedance-controlling electrode connected to the upper end of the base block between the second conductive patterns and the power-feeding terminal to control the impedance; an insulating layer formed on the upper surface of the base block; and a parasitic pattern layer including parasitic patterns formed on the insulating layer.
In accordance with yet another aspect of the present invention, there is provided a chip antenna including: a base block made of one selected from a dielectric material and a magnetic material and having a multilayered construction by stacking a plurality of sheet layers; first conductive patterns including side electrodes wound in a spiral form on a part of the base block, upper and lower electrodes connected to the side electrodes, and bending portions formed on the upper and lower electrodes; second conductive patterns disposed within the base block between the upper electrodes and the lower electrodes and connected in parallel with the first conductive patterns; a power-feeding terminal and a ground terminal, both connected to the first conductive patterns; an impedance-controlling electrode connected to the upper end of the base block between the second conductive patterns and the power-feeding terminal to control the impedance; and parasitic patterns formed on at least one sheet layer disposed between the sheet layer provided with the lower electrodes of the first conductive patterns and the sheet layer provided with the upper electrodes of the first conductive patterns, thereby forming an electromagnetic coupling with the first and second conductive patterns.
Those skilled in the art will appreciate that at least two of individual chip antennas in accordance with the aforementioned aspects of the present invention can be combined as a single chip antenna.